1. Field of the Invention
The present invention relates to a camera having a motion compensation device which shifts a compensation lens to compensate for motion affecting the camera. More specifically, the present invention relates to a motion compensation device having a protective member which protects the compensation lens.
2. Description of the Related Art
Optical systems project an image onto an image plane. Conventional image blur suppression devices suppress, or reduce, blurring of the image. A motion compensation device is a type of image blur suppression device, and compensates for motion incident upon the optical system. Motion is typically imparted to the optical system by vibrations in the optical system, or in a surrounding holding member. In general, conventional motion compensation devices cause a compensation lens to shift counter to the motion of the optical system so as to shift the image projected by the optical system relative to the optical system.
Conventional cameras use a motion compensation device to suppress image blur resulting from motion of the camera. Such motion is typically caused by hand tremors of the photographer.
A camera having a conventional motion compensation device is disclosed, for example, in Japanese laid-open patent publication No. H6-67246. In Japanese laid-open patent publication No. H6-67246, a compensation lens is retained by a lens frame. A coil is provided on the lens frame in both X- and Y-axis directions.
A support member that supports a yoke and a permanent magnet is fixed on a lens barrel for each coil in the X- and Y-axis direction. The yoke and permanent magnet, along with the coils, form a part of a drive mechanism that drives the lens frame.
A magnetic field is created between the yoke and permanent magnet. When the electrical current flows in the coils, the lens frame moves in a direction that is perpendicular to the optical axis of the camera, due to the driving force in the XY directions.
Therefore, the compensation lens and the drive mechanism (that is, the yoke, the permanent magnet, and the coils) together form the motion compensation device of the camera. This motion compensation device is integrated in a specific position inside a lens barrel of the camera.
Unfortunately, there is no protective member positioned adjacent to the compensation lens. Therefore, the compensation lens and drive mechanism are easily damaged by, for example, particles entering the lens barrel.
In addition, the drive mechanism is difficult to adjust due to its complex configuration. As a result, it is difficult to maintain the relative position of the compensation lens with respect to other lens groups in the camera, and with respect to an aperture unit and/or a shutter unit.
Further, it is difficult to install or replace the motion compensation device in the lens barrel, due to the various lenses and other components in the lens barrel. For example, during installation of the motion compensation device, the risk of inadvertently scratching the compensation lens, or damaging the drive mechanism, is very high.